Pressure switch



Mud! 1944- T. H. rARBRouGH ETAL, 2,345,023

PRESSURE SWITCH Filed Sept. 14. 1942 Zhwwvioms momasyarb r00 flea g; I

@Z/m '4 W Patented Mar. 28, 1944 UNITED STATES PATENT OFFICE raassmswrron Thomas H. Yarbrough and John Paul Wheat, Waco, Tex.

Application September 14, iua semi No. 45am (Cl. zoo-as) 1 Claim.

when the lubricant pressure is not in suiilcient I amount.

Another object of this invention is the provision of a device of theabove-named character which may be easily and quickly adapted to an.engine and its ignition system, whereby the latfor will be brokenshould the lubricant pressure failfrom some cause and is of aconstruction to permit the device to be conveniently adiusted foroperation on an engine having a battery ignition system. v With'theseand other objects in view as will become more apparent as thedescription proceeds.

the invention consists of such novel features of construction,combination and arrangement of 1 parts as will be hereinafter more fullydescribed and claimed.

For-a complete understanding of our invention, reference is to be had tothe fol owing description and accompanying drawing, n which Figure 1 isa vertical sectional view'illustrating I a pressureswitch constructed inaccordance with our invention.

Fig. 2 is a sectional view taken on the line 2-2 Fig. 3 is adiagrammatical view illustrating a wiring diagram showing the presentinvention cluding a base 6 on which is clamped or clinched a casing I. Adiaphragm 8. is located within the casing i and is held in positiononthe base I to form a pressure chamber 9 by the clinching of the casing5 on the base. A threaded nipple II is integral with the base 5 and isequipped with a bore I I extending from end to end thereof andconnecting with the pressure chamber 2. The nipple I0 is employed forconnecting the pressure switch I into a lubricant pressure line or aninternal combustion engine so that the pressure of the lubricant withinthe engine will act on the diaphragm for the purpose of flexing orexpanding said diaphragm. As soon as the pressure falls below apredetermined amount or fails the diaphragm returns to its initialposition.

A supporting member I2 is secured on the interior of the casing 1 in anywell known manner It arranged a selected distance from the diaphragm.The contact member I adjacent its free end and upon opposite facesthereof is provided with contact points I! and ii. A pin I1 is securedto the contact member I and is engaged by the diaphragm so that whensaid diaphragm is expanded or flexed by the pressure of lubricant withinthe pressure chamber 2 the contact member is caused to near or changefrom a normal position.

The stud bolt II also provides a mounting for.

a contact member II a portion of which par allels the contact member I4and is spaced therefrom. The contact member It includes a hookshapedportion extending about and spaced from the free end of the contactmember and has secured thereto contact points and 2| also an insulatingmember 22 disposed opposite to an adjusting screw 22. The adjustingscrew 22 threads into a bracket 24 a portion ofvwhich clamps between thecasing and diaphragm and thereby is held in a fixed position. The'setscrew 22 includes a knurled head 28 positioned under an opening 22provided in the casing I. The knurled head is provided with a kerf 21 tobe engaged by a screw driver or the like arranged to establish anelectrical connection therewith through the opening 22 so that the setscrew or djusting screw may be rotated in either direction. A lea!spring 20 is secured to the bracket 24 and rides against the knurledhead for retaining the set screw against accidental rotation. Also acoiled spring 29 may be arranged on the set screw and bears against thehead thereof and the bracket to assist in retaining the set screwagainst accidental rotation. The purpose of the set screw is to adjustthe hook-shaped portion I! of the contact member ll relative to thecontact points on the contact member It so as to adapt the use of thepressure switch 5 to either an ignition system of the battery type ormagneto type and which will be hereinafter more fully described.

An insulating block 30 is arranged between the contact members I and I!where they are mounted by the lug bolt II on the bracket I 2.

Also an insulating sleeve 2| is provided on the lug bolt ii to insulatethe latter from the contact member II.

The lug bolt l8 secures on the contact memher I! a contact finger I2which bears against a terminal 22 mounted on and insulated from vthecasing 7.

A suitable gasket 34 is provided in the casing to effect a seal'betweenthe latter and the base 2 to prevent the switch from losing pressurefrom the pressure chamber 9.

In Fig. 3 we have illustrated a portion of a battery type ignitionsystem for an internal- -combustion engine, the battery being indicatedby the character 35 one terminal of which is connected to an electricalground by a conductor 88. Th other terminal thereoi is connected to anammeter 31 by a conductor 38. An ammeter 31 is connected to an electricrelay 8! by a conductor 40. A terminal ll 01 the re lay it is connectedto an ignition switch 42 by a conductor 43. The ignition switch 42 iselectrically connected to the coil ll of the ignition system by aconductor 45. The coil 44 is connected to the usual distribution (notshown) by the lead It. A terminal 41 of the relay 39 has a conductor illconnected thereto and the latter is connected to the ground by amanually operated switch Bl. The present invention is electricallyconnected in the battery type ignitionsystem by having the terminal 33connected to the conductor 50 by a conductor 52. It is to be understoodthat the pressure switch i by having its nipple i threaded into alubricant pressure line oi the engine becomes electrically grounded inthe ignition system of said engine.

The relay 3! includes posts II and N electrically connected to theterminals II and 41 and are insulated from each other.

An electro-magnet 55 is included in the con- 'struction of the relay andis electrically connected to the terminal 38 and also is electricallyconnected to the post 84 by a conductor 56. a spring influenced contactarm 51 is pivotally mounted on the post 54 and acts as an armature forthe electro-magnet 55, and is adapted to be drawn in engagement with thepost. 53 when the magnet 55 is energized, the spring of the contact armacting to disengage said contact from the post 53 when the magnet 55 isdeenergized. The posts 58 and 54 are capabio of conducting electricity.When the ignition switch It is closed electric current may flow from the\battery through the ammeter, termiml "and post I to the ground by wayof the switch II when the latter is closed. As soon as theelectro-magnet is energized the contact arm I! is drawnthereagainst-andmgainst the post II so that electric current may alsoflow through the ignition switch to the coil II.

In adapting the present invention to operate,

a position for sustaining the contact points It.

and il spaced from the contact elements..." and ii when the chamber 9 isfree or pressure. This occurs when the engine is idle. When the engineis cranked or started the lubricant pressure is low or near zero and theswitch ll must be closed as well as the ignition switehior the startingof the engine. However, as soon as the lubricant pressure reachesnorm'al under the operation oi the engine, the diaphragm -exponds andmoves the contact member "so that the contact point I! engages thecontact point 2| connecting the conductor 80 to the ground through thepresent invention, the switch I is then manually open. When the deviceis operating as described, should the lubricant pressure cease from anycause, the diaphragm will return to its initial position permitting thecontact element II to assume its normal position disengaging the contactpoints I! and 20 interrupting the electric circuit of the magnet 65 sothat the latter becomes de-energized and the contact arm 51 under theinfluence of its spring then moves into the circuit breaking position.breaking the ignition circuit to the coil deenergizing the latter andconsequently stoppinig the operation of the engine. This will prevenioperation of the engine when the lubricant pressure fails andconsequently prevents the engine from damaging itself from want orlubricant.

As shown in Fig. 2 the spring 28 has a biiurcated end to straddle andcontact the knurled head of the adjusting screw for the purpose oiretaining the adjusting screw against accidental rotation. However, theadjusting screw may rotate relative to the bifurcated end when a screwdriver is placed in the kerf and rotated.

It will be seen through the use of our invention in the battery typeignition system that ii the ignition switch 42 is left closed when theengine is idle, the battery will be prevented irom discharging owing tothe iact that the pressure switch 5 is in circuit breaking position atthis time owing to the fact that it is free of any lubricant pressure.Therefore the present invention provides for automatically stopping theengine should the lubricant pressure tail and also will preventdischarge of the battery when the engine is idle ii the ignition switchis left closed.

While we have shown and described the preferred embodiment of ourinvention, it will be understood that minor changes in the construction,combination, and arrangement of parts may be made without departing fromthe spirit and scope of the invention as claimed.

Having thus described our invention, what is claimed is:

In an automatic pressure switch for an ignition system of an internalcombustion engine, a base. a diaphragm coacting with said base andproviding a pressure chamber, a casing clamped to the base for securingthe diaphrsgm to the latter, a threaded nipple formed on the base andconnecting the chamber to I lubricant pressure system of an engine andelectrically grounding the base to the engine, a contact membermountedin said casing and innuenced by said diaphragm, contact pointsarranged on opposite sides of the contact member, a second contactmember mounted in the casing and insulated from the first contlci memberand having a hook-shaped portion. contact points secured to saidhook-shaped portion ior coacting with the contact points carried by thefirst-named contact member, a terminal carried by said casing andadapted to be connected into an ignition system of the engine a contactfinger connecting said terminal to the second mentioned contact member,a brackat mounted in said casing, an adjusting screw carried by saidbracket for the adjustment 0i thesecond-named contact member relative tcthe first-named contact member, a spring member carried by the bracketand having a bii'urcated portion to engage the adjusting screw forsustaining the latter against accidental movement, said casing having anopening to permit a tool to extend therein to engage the adjustingscrew.

THOMAS H. YARBROUGH.

JOHN PAUL WHEAT.

